Electrode



ELLls May ELECTRODE Filed April 7, 1941 N NTOR. 262;; (I

w r I 5 w u 1 s Patented May 4, 1943 STATES PATENT FFICE 6 Claims.

The present invention relates to an electrode for picking up and conveying electrical current flowing through or adjacent a given surface.

In many arts it is desirable and necessary to apply an electrode to a surface for the purpose of passing an electric current between said surface and the electrode, as for example, when it is desired to measure or ascertain the properties of said current. In particular, when employing devices such as the electrocardiograph or other electrical diagnostic device, it is necessary to make a reasonably fizied'predetermined contact between the surface of a body and an electrode in order to accurately determine the characteristics of the existing electrical effect. Variation in the character of the connection obviously results in a variation in the current flow by varying the resistance at the point of cont-act and this factor has seriously limited the utility of many devices.

It is accordingly an important object of the present invention to provide an electrode assembly or contacting device adapted to make fixed, uniform and permanent contact.

A more specific object of the present invention contemplates the provision of an electrode adapted to be adjustedinto predetermined pressure relation upon an opposed surface for permanently maintaining contact until release.

Among other objects of the present invention are the provision of a construction as above which i is adapted to be freely and rapidly disassembled for repair and sterilization; to provide a construct-ion adapted for gripping application to the body without constriction of fluid flow or other normal functions; and to provide a construction 22 thereof;

Figure 3 is a sectional view taken through the assembly of Figure 2 on the line 3-3 thereof;

Figure 4 is a perspective exploded view showing the parts of the assembly in spaced disassembled relation;

Figure 5 is a perspective view of the gripping element adapted to grasp the holding band in operative position; and

Figure 6 is a perspective detailed view taken on the line 6-6 of Figure 3.

The illustrative embodiment disclosed in the figures oi the drawing for the purpose of exemplitying one preferred construction coming within the purview of the present, invention comprises a contact electrode 10 mounted on suitable portions relatively shiftable in a predetermined path within a preferably insulating housing l2. The housing l2 comprises an upper annular member l4, preferably of insulating material, and having a relatively large central aperture l6 cooperating with a lower housing member E8. The lower housing member is provided with a cylindrical portion 26 of generally the same diameter as the upper portion l4 and has an upwardly projecting central embossment 22 receivable within the aperture it on the said upper member it.

The upper and lower housing portions i4 and 18 are normally held together by machine screws 24 and it is particularly important to note that in the construction shown there is provided a plate 26 gripped between the two sections of the housing and having diametrically opposed extensions 23 projecting laterally a substantial distance on either side of the housing for a purpose which will hereinafter appear more in detail. It will be noted that the central portion of the plate 26 is apertured as at 35! and 32 to accommodate the central cylindrical embossment 22 of the lower housing portion and the clamping tact electrode and associated. portions of the elec tlode movable therewith as will hereinafter appear more in detail.

The electrode ii? in the present embodiment comprises a cylindrical side wall 38 complementarily receivable within the cylindrical recess 34 t and shiftable axially, the wall 33 merging with a somewhat convex axial end surface 49 providing th electrode contact surface. The interior of the electrode contains a complementary insert 42 of conducting material soldered in place and having an axially extending shank portion 44 extending axially through the housing. The shank Mi of the present embodiment is cylindrical in form and mounts a cylindrical sleeve 416 having a radial flange '38 at its lower extremity. clearly shown in Figure 2, the lower housing bushing provides a sleeve or bearing support ing the electrode for relative axial movement therewithin.

trode m is limited by impingementof the upper 7 As clearly shown in the figures. relative upward movement of the contact elec-- margin of wall 38 against the innermost extremity of the complementary recess. Movement of these parts is limited in the other direction by a stop collar 50 embracing the upper extremity of th electrode shank 44.

Attention is particularly directed to the fact that the collar is releasably attached to the shank by means of a detent comprising a spherical member 52 received within a cylindrical, radially disposed channel in the collar and yieldably pressed into an annular channel 54 formed about the periphery of the shank M by means of a helical coil spring 56. A set screw 58 abuts the spring 56. Attention is directed to the fact that the collar 50 is provided with an enlarged shouldered recess to complementarily receive the upper extremity of the sleeve 46, thus fixedly axially disposing th sleeve upon the shank M for movement therewith at all times.

Attention is directed to the fact that a helical coil spring 60 normally urges the contact electrode Ill outwardly and downwardly to its limiting position as defined by the stop collar 59. When urged into the housing, the contact electrode l experiences a tensioning force applied by the spring 60 which force is a function of the distance to which the contact electrode is retracted. In short, the force is equal, fixed and predetermined ior any position intermediate of the path of travel of the electrode.

Particular attention is directed to the fact that the stop collar 50 bears inscribed thereon an annular marking line or indicia 62 disposed in a predetermined axial plane. Accordingly, when this line resides in alignment with the upper margin of the upper housing section l2 acting as a relatively fixed datum plane, the spring exerts a predetermined force upon the contact surface 40. At all times with the parts so disposed, this force will be constant, maintaining predetermined electrical contact.

From the foregoing, it will be apparent that the present device is subject to rapid dismantling by merely pressing the upper extremity of the shank 44 downwardly with a sufficient force to release engagement of the detent sphere 52. When so released, the entire electrode, including the shank M, insert 42 and electrode III, are released for separation from the assembly for cleaning, replacement or repair. lAt this time, the clamping screws 24 are accessible for release. It will be apparent from the foregoing that assembly proceeds in converse order, thus facilitating and simplifying manufacture.

The present invention provides means for maintaining the assembly permanently gripped in operatively relationship and to this end the outwardly extending sections project to some distance radially outwardly of the housing and mount thereon a strap or band 64. One extremity of the band, as seen at the left-handmost portion of Figure 2, is permanently secured adjacent an extremity of the associated arm 28, being passed through a slot 65 formed therein and folded over as at 68 in such a manner as to resist withdrawal. The opposite extremity of the band 54 projects through a slot 10 in the opposite arm 28 and projects somewhat therebeyond, being normally frictionally clamped or gripped at any adjusted position by means of a clasp arrangement shown more in detail in Figures 2, 3, and 6. The clamping means oomprises a generally flat upper wall 12 terminating at on extremity in a downwardly projecting lug 28. The lug and aperture connection provides a pivot connection, permitting relative longitudinal movement of the lug within the recess. A headed pin 18 threadedly engaged with the arm 28 as at 8i! extends through the central part of the wall 72 and mounts a helical compression spring 82 which normally urges the gripping member downwardly whereby the lower edge of a gripping flange il ilocated in operative association with an opposed edge of the slot 19 coacts therewith to clamp the strap against withdrawal. In other words, it will be seen that the flange, in cooperation with the opposed edge of the slot, normally exerts a strutting action under the influence of spring 82 to effectively resist retrograde movement of the strap in the slot. On the other hand, the strap can be drawn upwardly in the slot by virtue of the fact that such actuation tends to lift the gripping flange away from operative relation. It should be noted, moreover,

that the gripping plate is provided with opposed finger clips 35 to permit manual release at times when the strap 54 is to be withdrawn.

In light of the foregoing description, it will be apparent that in applying the present device in operative relation the strap is released and wrapped about the member with which contact to be made. Thus, in Figure 2 I have illusrated the application of the invention to contact with the forearm, although it will be understood that the device is applicable in innumerable other relations. In effecting application as indicated in Figure l, the strap is drawn through the aperture 10 until such time as the contact electrode is compressed within its recess and the inscribed marking 62 lies in alignment with the upper margin of the housing. In this position, the clasp operates to lock the strap64 in the position shown and contact remains uniform and permanent until released by lifting the manually manipulatable lugs 86 to release the strap.

It is important to note that the present invention permits permanent maintenance of electrical contact without unduly constricting the body to which the electrode assembly is applied. Thus it will be noted that aside from the application of a pressure just beneath the contact electrode surface, the only restraint imposed upon the body is an equal force diametrically opposed. In other words, intermediate portions of the body are free from constraint since they are spaced from the strap by virtue of outwardly projecting arms 28. In its broadest aspect, the present invention contemplates the use of other suitable means adapted I4 freely insertable within a recess 16 in the arm to maintain a spacing between the gripping parts and the body contacted at points adjacent and about the area of contact. In view of the foregoing, various other means will occur to those skilled in the art whereby gripping means are restrained from wrapping closely about the body. Thus, for example, for the strap 64 may be substituted a curved, bow-like rigid member connected to the housing by means of intervening extensible means at its extremities. So also, the invention contemplates in this broad aspect the use of a clamp projecting laterally from the housing and having means oppositely disposed with respect to the contact electrode for applying pressure at a predetermined point only.

The present invention additionally provides for releasable interconnection with cord tip terminals and to this end the shank 44 is axially bored as at 88 to receive a terminal 90 of the so-called spring or banana type receiving the end of a conducting cord 92.

The present invention provides a simple and effective construction adapted to make and maintain a permanent but releasable electrical contact with an adjacent surface under test. The invention, moreover, provides for easy adjustment of the electrode to a fixed predetermined pressure determined by a fixed spring cooperating with alignable indicia. The device, moreover, applies and maintains pressure without interference to circulation or undue gripping of the parts under test and is freely releasable under the control of the operator.

It is thought that the invention and numerous of its attendant advantages will be understood from the foregoing illustrative description and it is obvious that numerous changes may be made in the form, construction and arrangement of the several parts without departing from the spirit or scope of the invention or sacrificing any of its attendant advantages, the form herein described I being a preferred embodiment for the purpose of illustrating the invention.

I claim: 1. In a contact electrode assembly of the class described, an electrode supporting housing movement thereof, oppositely directed arms projecting outwardly from the sides of said housing a substantial distance and being spaced from the plane of the contact surface of said electrode a substantial distance throughout their extent. a gripping band engageable with said arms adjacent the outer extremities thereof and adapted to embrace a body to urge the contact electrode into engagement therewith, said arms being adapted to hold the gripping band away from the body surfaces throughout a substantial extent thereof, means for longitudinally adjusting said band with respect to at least one of said arms for determining the tension thereof, and clamping means adapted to lockingly engage the 'band with the said arm against retrograde move ment for maintaining the parts in operative relation.

2. An electrode assembly of the class described, comprising an electrode supporting frame, a

spring pressed contact electrode mounted on said frame for relative longitudinal movement in a predetermined path, said contact electrode including a shank extending through a portion of said housing and a retaining member mounted on said shank adjacent an opposite portion of said housing, said retaining member comprising means for releasably engaging said shank against relative longitudinal movement and adapted to releasably maintain the parts in operative relation, said releasable member comprising a yieldably mounted detent operative to release upon the application of a predetermined axial pressure to the shank.

3. In a contact electrode assembly of the class described, an electrode supporting housing mounting a contact electrode therein for relative movement in a fixed path, said contact electrode having a contact surface disposed outwardly beyond one extremity of said housing, predetermined resilient means urging said contact electrode to said position, projecting means on said housing extending oppositely outwardly a substantial distance and being substantially spaced from the plane of said contact surfaces,

and flexible tensioning means having engagement with said projecting means at points substantially spaced from said contact electrode and adapted to be adjustably tensioned with respect to said projecting means for urging the contact means into predetermined gripping relation with a body member, said projecting means being rigid and being disposedand arranged to substantially space said means and adjacent portions of said flexible gripping means a substantial distance from the surface of said body member.

4. In a contact electrode assembly of the class described, an electrode supporting housing mounting a contact electrode therein for relative movement in a fixed path, said contact electrode having a contact surface disposed outwardly beyond one extremity of said housing, predetermined resilient means urging said contact electrode to said position, projecting means on said housing extending oppositely outwardly a substantial distance and being substantially spaced from the plane of said contact surfaces, and flexible tensioning means having engagement with said projecting means at points substantially spaced from said contact electrode and adapted to be adjustably tensioned with respect to said projecting means for urging the contact means into predetermined gripping relation with a body member, said projecting means being rigid and being disposed and arranged to substantially space said means and adjacent portions of said flexible gripping means a substantial distance from the surface of said body member, and said contact electrode having a portion extending beyond an opposite extremity of said housing and being provided with indicia adapted to indicate a predetermined resilient tension on said contact electrode when the said extending portion reaches a predetermined position with respect to the housing.

5. An electrode assembly of the class described comprising a housing, contact electrode means shiftable longitudinally of said housing in a predetermined path and presenting a contact surface outwardly of one extremity of the housing, said contact electrode means having an extension projecting longitudinally through said housing, a retaining means yieldably engaging said extension, said housing having a recess adapted to receive said retaining means, yieldable means acting on said contact electrode to urge said electrode outwardly of its extremity of the housing, said contact electrode means and extension being yieldably movable against said tension to a position where the retaining means is spaced from its recess and in a position adapted to be manually engaged and released from said extension.

6. An electrode assembly of the class described, comprising a housing having a central guideway, a recess for a contact electrode at one extremity of the guideway and a recess for a retaining member at the other extremity, a contact electrode in said first named recess and having an extension projecting through said guideway and a retaining member yieldably engaged with said extension adjacent said second named recess, yieldable means normally urging the contact electrode outwardly of its extremity of the housing and disposing said retaining means within the second named recess, said parts being yieldable to a position where the retaining means is spaced from its recess and adapted to be yieldably removed for disassembly.

FRANCIS C. ELLIS. 

